Terrazzo grinder



Oct. 6, 1942. P NP 2,298,228

TEBRAZZO GRINDER Filed Ju1 2o, 1940 -4 sheets-sheet 1 Harold J. Pond andCarl 0. Larson Oct.'6, 1942. H. J. POND EI'AL 2,298,228

TERRAZZO GRINDER Filed July 20, 1940 4 Sheets-Sheet 2 e9 61. P1. g} 47 m&

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, TERRAZZO GRINDER Filed July 20, 1940 4 Sheets-Sheet s Fig.5 3mm HaroldJ. Pond and Carl 0. Larson dw figi zw Oct. 6, 1942. H. J. POND ETAL2,298,228

TERRAZZO GRINDER Fiied July 20, 1940 4 Shepts-Shet 4 o u M "Harold J.Pond and. Cad O Larson Patented Oct. 6, 1942 TERRAZZO GRINDER Harold J.Pond and Carl 0. Larson, Minneapolis, Minn., assignors to AdvanceMachine Company,

Inc., Minneapolis, Minn.,

Minnesota a corporation of Application July 20, 1940, Serial No. 346,623

10 Claims.

Our invention relates to portable tools and particularly to motor drivengrinders adapted to be used for grinding vertical surfaces of terrazzoand similar materials used in building construction.

An object of the invention resides in providing a grinder capable ofcovering an extended vertical surface with minimum repositioning of theentire grinder.

Another object of the invention resides in providing a grinder capableof being used with angularly disposed surfaces.

An object of the invention resides in providing a grinder which will notrequire accurate setting of the same with reference to the surface to beground.

A still further object of the invention resides in providing a grindercapable of being easily and. quickly transported.

A feature of the invention resides in providing a portable grindercapable of being easily and quickly brought up to the surface to beground and moved along the same.

An object of the invention resides in providing a portable grinder whichis easy to manipulate, and in which the weight of certain of the partsis counter balanced by the weight of the motor.

A still further object of the invention resides in providing a basehaving an upright carried thereby and pivotally supporting a motorcarrying a pair of jointed arms and in one of which the grinding wheelis rotatably supported.

An object of the invention resides in providing pivot means between themotor and upright permitting the motor to swing about two axes at rightangles, one of said axes being substantially horizontal.

Another object of the invention resides in supporting the arms formovement in planes shiftable out of parallelism.

An object of the invention resides in providing pivot means between thetwo arms whereby the arms may swing about two aXes substantially atright angles to one another.

Other objects of the invention reside in the] novel combination andarrangement of parts and in the details of construction hereinafterillustrated and/ or described.

In the drawings:

Fig. 1 is a plan view of a portable tool illustrating an embodiment ofour invention.

2 is an end elevational view of the structure shown in Fig. 1.

Fig. 3 is a side elevational view of the structure shown in Figs. 1 and2.

Fig. 4 is a cross sectional View taken on line 4-4 of Fig. 2 and drawnto a greater scale.

Fig. 5 is a view similar to Fig. 4 taken on line 5-5 of Fig. 1.

Fig. 6 is a cross sectional view taken on line 66 of Fig. 1 and drawn tothe same scale as Figs. 4 and 5.

Fig. 7 is a fragmentary plan View taken on line 'l'! of Fig. 2.

Fig. 8 is a view similar to Fig. 3 showing the tool used for grindingunder cut risers of stairs.

Fig. 9 is a view similar to Fig. 3 showing the tool arranged to cutbeveled coves.

Fig. 10 is a fragmentary elevational view taken on line llll0 of Fig. 3.

The invention comprises a base it which may be constructed from sheetmetal or a casting, or which may be constructed in any other suitablemanner. This base is triangular in shape, as best shown in Fig. l, andis supported at one of the corners thereof by means of a caster wheel llwhich is mounted to swivel on a fork [2 in the customary manner. At theother corners of the base the same is supported on wheels l3 and M whichare mounted in identically the same mariner. For this reason only themethod of mounting the wheel [3 will be described in detail. This wheelis carried on a pintle l5 which is journaled in a fork I6. Fork It has astud I! extending upwardly therefrom which is rotatably mounted in abearing formed in the base IE! by drilling the same, as indicated at H8.The fork i6 is of larger dimensions than the stud I! so that the sameprovides a shoulder on which the base l0 rests. The stud IT projectsupwardly beyond the base l9 and is formed in its projecting end with avertically extending slot [9. In this slot is disposed a handle 21 whichis pivoted thereto by means of a pin 22 extending jointly through saidstud and handle. The handle may be swung upwardly on the pin 22 or movedto a horizontal position, as shown in Fig. '7. When in a horizontalposition the handle 2| may be moved from the full line position shown insaid figure to the dotted line position or vice versa. The handle 2| isheld in either of its two positions shown in Fig. '7 by means of spacedlugs 23 and 24 between which the handle may drop. When the handle isbetween the lugs 23 the wheel 13 is held in a position parallel with theforward edge 25 of the frame l8 and when said handle is between the lugs24 said wheels are at right angles to said edge.

Immediately above the caster wheel H is provided an upright 26preferably constructed as a casting which has a foot 21 formed thereonand which is bolted to the base II) by means of cap screws 28. Theupright 26 is formed with a goose neck 29 which is disposed above theintermediate portion of the base I0.

The invention utilizes an electric motor 3| provided with a corestructure 32 and having end bells 33 and 34 attached thereto. In theseend bells is journaled a shaft 35 which is attached to the rotor of themotor. The core structure 32 of the motor has attached to it a number offeet 36 which normally serve as a base for the motor. These feet haveattached to them two spaced U-shaped brackets 31 and 38 which are boltedto said feet by means of cap screws 39. The two brackets 31 and 38 havebearings 4| formed thereon which journal a shaft 42. A hanger 43,attached to the goose neck 29, is provided with a bore 44 which receivesthe shaft 42, said hanger being disposed between the bearings 4|. Bymeans of this construction the motor 3| is mounted for swinging movementabout the axis of the shaft 42 which is substantially parallel to theaxis of the motor shaft 35 and which is eccentric relative thereto. Thehanger 43 is constructed with an ear 45 which overlies the end 46 of thegoose neck 29. A bolt 41 disposed with its axis in a horizontal positionextends through the ear 45 and through the end 46 of the goose neck 29and provides a pivot having a horizontal axis whereby the entire motorand hanger may be moved in a vertical plane. A look bolt 48 also extendsthrough the ear 46 and through a slot 49 in the end 46 of the goose neck29. By means of this lock bolt the motor 3| and hanger 43 may be held inangularly adjusted position.

The invention further embodies two jointed arms and 52, the arm 5| beingattached to the motor BI and the arm 52 carrying a suitable tool holder53. The arm 5| is attached to the motor 3| in the following manner:Secured on the end bell 33 by any suitable means, not shown, is a flange54 through which the motor shaft extends. The arm 5| is constructed intwo parts 55 and 56 which have channel-shaped portions 51 at theoutermost edges and which have web portions 58 therebetween. The webportions 58 are bolted together at intervals by means of bolts 59.flange 6| which is bolted to the flange 54 by means of cap screws 62.This flange is so arranged with reference to the flange 54 that the axisof the shaft 42 substantially intersects the center line of the arm 5|.By means of this construction the arm 5| is rigidly attached to themotor 3|. The end of the part 55, of arm 5|, opposite the flange BI, isconstructed to provide a case in which is disposed a pulley attached tothe shaft 35.

The two arms 5| and 52 are connected together by means of aconstruction, best shown in Fig. 5. The part 56 of arm 5| has formed onit a flange 63-, while the corresponding portion of the part 56 isprovided with a cap 64. These two parts form a case having a compartment65 within the same in which is disposed a pulley 66. Pulley 66, ismounted on a shaft 61 which is journaled at one end in a ball bearing 68mounted in the cap 64. A cover 69 covers the end of the shaft 51'.Rotatably mounted in a socket H in the flange 63 is a head 12. This headcarries a ball bearing 13 which journals the other end of the shaft 61.The ball bearing 13 fits against a shoulder 14 in the head 12, while theball bear- The part 56 is provided at one end with a a ing 68 similarlyfits against a shoulder 15 in the cap 64. The two ball bearings areurged toward one another by means of a nut 16 screwed on one end of theshaft 61 and one member 11 of a universal joint 18 screwed on the otherend of the said shaft. By means of this construction the head 12 isrotatably held within socket 1| and against the flange 63.

The arm 52 is constructed in identically the same manner as the arm 5|being formed with two parts BI and 82, bolted together in the samemanner. The part 82 is constructed with a sleeve 63 projecting outwardlytherefrom which is disposed opposite the head 12. Head 12 is providedwith two ears 84 projecting outwardly therefrom which overlie the sleeve63. These ears have screwed in them conical pivots 85 which are seatedin jewels 86 mounted in the sleeve 83. The pivots 85 are held inadjusted position by means of set screws also screwed in the ears 84. Bymeans of these pivots the arm 52 is guided for swinging movement aboutan axis through the said two pivots which is parallel to the plane ofmovement of the arm 5| about shaft 42 and at right angles to the axis ofthe shaft 61.

The part 8| of arm 52, opposite the sleeve 83, is constructed with a hub81 which is provided with two ball bearings 88 and 89. These ballbearings journal a shaft 9| which has secured to the end of it the othermember 92 of the universal joint 18. This universal joint includes aring 93 of flexible material such as rubber impregnated fabric, leatheror the like, which is bolted to the two members at alternately spacedlocations by means of cap screws 94. This universal joint forms adriving connection between the shafts 61 and 9| which permits the arm 52to swing about the pivots 85 to a limited extent.

The tool holder 53 of the invention is attached to the end of the arm 52and is shown in detail in Fig. 4. This tool holder is constructed andmounted as follows: At the end of the part 8| of arm 52 is provided aboss 96 which is bored as indicated at 91 to receive the end of atubular housing 98. The tubular housing 98 has a flange 99 formedthereon which is attached to the boss 96 by means of cap screws IOI. Thetubular housing 98 has mounted in it at the ends thereof ball bearingsI02 and I03 which rotatably support a shaft I04. The two bearings I02and I03 are held in position upon the shaft I04 by means of a nut I05screwed on the outer end of the shaft and by means of spacer sleeves I96and I01. Adjacent the sleeve I91 is a pulley I08 which is urged againstthe sleeve I01 by means of another nut I09 screwed on the inner end ofsaid shaft. The pulley I08 is disposed in a compartment I38 formed atthe end of the arm 52 by means of the boss 96 and a cap I31 formed onthe part 82 of said arm. The bearing I03 floats in the end of thehousing 88, while the bearing I02 is clamped in said housing by means ofa shoulder III formed therein and a clamp ring II2 secured to the end ofsaid housing by means of screws H3.

The nut I05 screwed on the end of shaft I94 is threaded as indicated atII 4 to receive one of the elements II5 of a universal joint H6. Theother element II1 of this universal joint is attached to a short shaftII8 on which the tool to be operated by the device is mounted. In theinstant invention the device is designed as a grinder and has a grindingwheel II9 mounted on the shaft II8. This wheel is held in position bymeans of a nut I2I screwed upon the end of the shaft H8. The two membersH5 and H1 of the universal joint H6 are alternately secured to two ringsI22 constructed of a flexible material similar to the ring 93 of theuniversal joint 18. This construction provides a flexible mounting forthe wheel I I9 and, at the same time, serves to drive the said wheelfrom shaft I04. To take the end thrust imparted to the wheel H9 theshaft H8 is provided with a socket I23 which receives aspheroidal-shaped protuberance I24 formed on the forward end of the nutI65. This arrangement permits of angular operation of the shaft I I8with respect to the shaft I04 and causes intersection of the axes of thetwo shafts to be maintained at the center of the socket I23.

The various shafts of the invention are driven in the following manner:As previously stated the shaft 35 of motor 3| has mounted on it a pulley59 disposed within the interior of the case 48 in arm 5| at the localityof the flange 6!. This pulley carries a belt I25 which may be a V-belt,and which passes over the pulley 66, mounted on shaft 61, which waspreviously referred to. Shaft 61 drives shaft 9| through the universaljoint 18. Mounted on the shaft 9| is a pulley I26 which is arranged toreceive two V-belts I21. The two belts I21 also pass over the pulleyI88, thereby affecting a drive between the shaft SI and I134. The shaftI94 drives the shaft H8 through the universal joint I I 6.

In order to permit of wet grinding of the terrazzo or other material tobe ground, a reservoir I21, for water, is provided, which is mounted ona bracket I28 secured to the uppermost portion of the goose neck 29 ofthe upright 26. This reservoir has a hose I29 connected to it. A valve I3| controls the flow of water through the said hose. The hose I29 isconnected to the inlet side of a pump I 38 mounted on the arm 5|. Thispump has a pulley I32 on it which is driven by a belt I33 from a pulleyI34 on the end of the motor shaft 35 of motor 3|. The pump I30 hasconnected to it another hose I35 which follows along the two arms 5| and52, and which 1 is connected to a hose fitting I36 screwed into the capI31 formed on the part 82 of arm 52. The shaft I84 has a bore I39 in itand in which is mounted a tube I4I. This tube is flanged at its end andis held in position in the cap I31 by means of the hose fitting I36.This tube extends through a bore I43 in the nut I05 and up to the end ofthe protuberance I24 and communicates with a bore I42 in the shaft I I8.By means of this construction water is led under pressure directly tothe shaft H8 from which is flows into the cavity I44 within the grindingwheel H9 whereby the water may be fed to the work as the grinding wheeloperates. A revoluble guard I 45 rotatably mounted on the tubularhousing 98 protects the grinding wheel H9 and also prevents any waterwhich may leak out past the nut I and the shaft H8 from following backalong the tool holder 53.

Attached to the arm 52 is a handle I46 by means of which the tool holder53 may be manipulated.

The method of using the invention is as follows: Our improved portabletool when used as a grinder is particularly designed to grind verinFigs. 2 and 3 and the motor 3| adjusted through the two bolts 41 and 48so that the arm 5| extends in a vertical plane. The entire grinder isthen moved up to the work so that the grinding wheel H9 is within aninch or less of the surface to be ground. When the grinder is in suchposition the tool holder 53 is manipulated by means of the handle I46which is secured to arm 52 and is moved in the plane of the surface tobe ground both in a horizontal direction and in an up-and-downdirection. The pivot formed by the shaft 42 permits of horizontalmovement of the tool holder 53, while the pivot afforded by the rotationof head 12 in the bore 1| of arm 5| accommodates vertical movement ofthe said head. Due to the use of the universal joints 18 and I IS, thegrinding wheel II 9 may be moved toward and from the surface to beground and at the same time will readily adjust itself to the contour ofthe surface, thus compensating for variations in the positioning of theentire grinder with reference to the work to be ground. As a section ofthe surface to be ground is completed, the entire device is shifted inthe direction of the extent of the surface to be ground, which is madepossible by the arrangement of the wheels I3 and I4. The wheel II beinga caster wheel, follows along with the wheels I3 and I 4, which lateralwheels serve to guide the device in the proper direction.

It frequently occurs that base boards are constructed at an angle asillustrated in Fig. 9. When the grinder is to be used for grinding sucha surface the hanger 43 is tilted, as shown in Fig. 9, so that thegrinding wheel faces in the proper direction. Where a cove is providedbetween the base and the floor, a wheel I41 is employed which has arounded corner I48. This permits of grinding the cove at the same timethe base is being ground.

In the surfacing of risers of stairs a platform is built which restsupon a number of the stairs and which is arranged to support the grinderas shown in Fig. 8. The platform is indicated by the reference numeral I5| in Fig. 8. In this View the risers have been shown as incliningforwardly. When a riser of this type is to be surfaced the hanger 43 isadjusted as shown in Fig. 8, and a stone I52 such as illustrated isemployed which gives sufficient clearance for the cap I31 of arm 52. Inthe grinding of these various surfaces the grinder is manipulated inidentically the same manner as when used for grinding vertical surfaces.

It will be noted that the grinder, when the two arms are jackknifed, isless in width than in length. In transporting the machine to and fromthe work it hence becomes desirable to move the machine in a directionat right angles to the direction of travel of the machine duringgrinding. This may be easily and quickly accomplished by raising thehandles 2| and swinging the studs I1 from the position shown in fulllines in Fig. '7 to that shown in dotted lines in which the handle isheld between the lugs 24. In the latter positions of the wheels, thegrinder may be wheeled fcrwardly through narrow door openings andmanipulated about in tight quarters. Adjustment of the machine towardand from the work may also be accomplished by swinging the wheels, asabove noted, and after the machine has been brought into proper positionwith reference to the work, the wheels may be turned back intoparallelism with the surface to be ground.

The advantages of our invention are manifest.

same becomes unnecessary.

The grinder is extremely compact and has a wide range of operation. Withour invention considerable work may be done with one setting of thegrinder so that frequent positioning of the The guide wheels of thegrinder may be moved to-either of two positions whereby the grinder maybe moved along the surface being ground, or moved toward and from thesame. By means of the various pivots provided, the grinding wheel may bepositioned to grind vertical surfaces and inclined surfaces such as arefrequently found in building construction. By the use of the twouniversal joints the wheel can be made to adapt itself to the contour ofthe surface to be ground and at the same time inaccurate positioning ofthe machine with reference to the surface to be ground will have noeffect upon the results.

The motor being used as a counter balance for the arms the weight of thegrinder is held at a minimum and at the same time the tool is easy tooperate and manipulate. With our invention the surfaces ground may bewet ground so as to avoid dust and to produce the results possible withwet grinding. Our improved portable tool can be constructed at a nominalexpense and is sturdy in construction and serviceable in operation.

Changes in the specific form of our invention, as herein disclosed, maybe made within the scope of what is claimed without departing from thespirit of our invention.

Having described our invention, what we claim as new and desire toprotect by Letters Patent is:

1. In combination a base, an upright carried by the base, an electricmotor having a shaft, pivot means between said motor and upright forguiding said motor for movement to cause the shaft thereof to swing in asubstantial vertical plane, means for locking said motor from movementabout said pivot means, a pair of jointed arms, one of said arms beingconnected to said motor, a movable tool holder carried by the other ofsaid arms, and means supported by said arms and driven by the motorshaft for operating said tool holder.

2. In combination a base, an upright carried by the base, an electricmotor having a shaft, pivot means between said motor and upright forguiding said motor for movement to cause the shaft thereof to swing in asubstantially vertical plane, an arm attached to said motor, a secondarm pivoted to said first arm about an axis parallel with the axis ofsaid motor, a rotatable tool holder carried by said second arm androtatable about an axis substantially parallel with the axis of saidmotor, and transmission means carried by said arms and driven by saidmotor shaft for operating said tool holder.

3. In combination a base, an upright carried by the base, an electricmotor having a shaft, pivot means between said motor and upright forguiding said motor for movement to cause the shaft thereof to swing in asubstantially vertical plane, an arm attached to said motor, pivot meansfor guiding said arm and motor for swinging movement about an axissubstantially parallel with the axis of said motor shaft, arevolublehead pivoted to said arm about an axis parallel with the axis of saidmotor, said arm being movable in a plane at right angles to the axis ofsaid motor, a second arm pivoted to said head about an axis parallelwith the plane of movement of said first named arm and adapted to swingin a plane shiftable out of parallelism with the plane of movement ofsaid first named arm, a rotatable tool holder mounted on said secondnamed arm, and transmission means carried by said arms for driving saidtool holder from said motor shaft.

4. In combination a base, an upright carried by the base, an electricmotor having a shaft, pivot means between said motor and upright forguiding said motor for movement to cause the shaft thereof to swing in asubstantially vertical plane, an arm attached to said motor, pivot meansfor guiding said arm and motor for swinging movement about an axissubstantially parallel with the axis of said motor shaft, a second armpivoted to the first arm for swinging movement in a plane substantiallyparallel to the plane of movement of the first arm, a universal jointbetween said arms for accommodating movement of said second arm in aplane out of parallelism with the plane of movement of the first arm, atool holder, means for rotatably supporting said tool holder on saidsecond arm for movement about an axis substantially parallel to the axisof said motor shaft, transmission means carried by said arms for drivingsaid tool holder from said motor shaft, said transmission meansincluding a universal joint concentrically arranged with respect to theuniversal joint between said arms.

5. In combination a power driven shaft adapted to be disposed in asubstantially horizontal position, an arm pivoted for movement about anaxis extending in the same direction as the axis of said shaft andadapted to swing in a plane at right angles to said shaft, a headpivoted to said arm and adapted to rotate in a plane parallel with theplane of movement of said arm, a second arm pivoted to said head andadapted to move about an axis parallel with the plane of movement ofsaid first named arm and to rotate with said head in a plane shiftableout of parallelism with the plane of movement of said first named arm, atool holder rotatable about an axis at right angles to the plane ofmovement of said second named arm, transmission means carried by saidarms for driving said tool holder from said power driven shaft, saidtransmission means including a universal joint concentrically arrangedwith reference to the axis of said head.

6. In combination a power driven shaft adapted to be disposed in asubstantially horizontal position, an arm pivoted for movement about anaxis extending in the same direction as the axis of said shaft andadapted to swing in a plane at right angles to said shaft, a headpivoted to said arm and adapted to rotate in aplane parallel with theplane of movement of said arm, a second arm pivoted to said head andadapted to move about an axis parallel with the plane of movement ofsaid first named arm and to rotate with said head in a plane shiftableout of parallelism with the plane of movement of said first named arm, atool holder rotatable about an axis at right angles to the plane ofmovement of said second named arm, a pulley on said power driven shaft,a shaft carried by said first named arm and disposed substantiallyconcentric with the axis of rotation of said head, a pulley on saidsecond named shaft, a third shaft rotatably mounted in said second armand disposed opposite said second named shaft, a universal joint betweensaid second named shaft and third named shaft, a pulley carried by saidtool holder, and a belt extending about the pulley on said tool holderand the pulley on the third named shaft.

7. In combination a base, an upright carried by the base, an electricmotor having a frame and a shaft journaled in said frame, pivot meansbetween said motor frame and upright for guiding said motor for movementto cause the shaft thereof to swing in a substantially vertical plane,an arm secured to said motor frame, pivot means for journaling said armfor swinging movement about an axis parallel with the axis of said motorshaft, a revoluble head pivoted to said arm about an axis parallel withthe axis of said motor, a second arm pivoted to said head about an axisparallel with the plane of movement of said first named arm and adaptedto swing in a plane shiftable out of parallelism with the plane ofmovement of said first named arm, a rotatable tool holder mounted onsaid second named arm, and transmission means carried by said arms anddriving said tool holder from said motor shaft, said transmission meansincluding a universal joint concentrically arranged With respect to theaxis of said head.

8. In combination a base, an upright carried by the base, an electricmotor having a shaft, a hanger pivoted to said upright about asubstantially horizontal axis and adapted to swing in a substantiallyvertical plane, pivot means between said hanger and motor having an axisparallel with the plane of movement of said hanger whereby the motor mayswing in a plane at right angles to the plane of movement of saidhanger, an arm attached to said motor, a second arm pivoted to saidfirst arm for movement about an axis substantially parallel with theaxis of said motor shaft, a rotatable tool holder mounted for rotationon said second arm about an axis substantially parallel to the axis ofsaid motor shaft, and transmission means carried by said arms fordriving said tool holder from said motor shaft.

9. In combination a base, an upright carried by the base, an electricmotor having a shaft, a hanger pivoted to said upright about asubstantially horizontal axis and adapted to swing in a substantiallyvertical plane, pivot means between said hanger and motor having an axisparallel with the plane of movement of said hanger whereby the motor mayswing in a plane at right angles to the plane of movement of saidhanger, a pair of jointed arms, one of said arms being attached to saidmotor and being adapted to swing with said motor in a plane at rightangles to the shaft of said motor, a rotatable tool carried by the otherarm, and means for driving said tool from said motor shaft.

10. In combination a base, an upright carried by the base, an electricmotor having a shaft, pivot means between the motor and upright forguiding the motor for movement about two axes at right angles to oneanother, an arm attached to said motor, a second arm, pivot meansbetween the two arms for guiding the arms for relative movement abouttwo axes substantially at right angles to one another, a rotatable toolcarried by the second arm, and transmission means carried by the armsfor driving the tool from the motor shaft.

HAROLD J. POND. CARL O. LARSON.

